A known absorbent core for an absorbent article has a side that faces the absorbent article's topsheet formed into a projecting-and-depressed shape. Patent Document 1, for example, discloses a sheet-like conjugate absorbent core that consists of a conjugate core made by superposing a superabsorbent core sheet on a liquid-impermeable sheet. The liquid-impermeable sheet and the superabsorbent core sheet are joined together at a plurality of long-and-narrow joining portions that are parallel to one another, and channels are formed between the liquid-impermeable sheet and the superabsorbent core sheet in the respective spaces between adjacent joining portions.
Further, Patent Document 2 discloses an absorbent core, which consists of a laminate of a nonwoven fabric layer and a fibrous web layer, for an absorbent article. The laminate includes first network regions that are thin and have high density, and second network regions that are thick and have a lower density than the first network regions. The surface of the fibrous web layer is bulky and has projections and depressions. The first network regions are arranged in the form of bands intersecting one another, whereas the second network regions are provided as partitioned layers surrounded by the first network regions.
These absorbent cores come into contact with the topsheet only at their projections. Therefore, when fluid is excreted on the topsheet, the spaces between the projections provide improved fluid permeability for low-viscosity fluid such as urine. However, for high-viscosity fluid such as menstrual blood, fluid may be transferred through portions in contact with the projections, but is less likely to be transferred at portions that are not in contact with the projections. This may result in fluid residue on the topsheet and tends to deteriorate the dry feel of the topsheet.
Further, in cases where high-viscosity fluid such as soft feces is excreted on an absorbent article having such an absorbent core, the high-viscosity fluid is retained in the depressions between the projections of the absorbent core. Since the high-viscosity fluid is retained in the depressions in its as-is viscous state, the retainability of the fluid in the absorbent core is poor, causing the fluid to flow in the absorbent core due to a wearer's movement. Furthermore, in cases where body pressure etc. is applied on the article, the high-viscosity fluid is prone to cause wet-back from the topsheet.
Patent Document 1: JP 7-155596A
Patent Document 2: JP 2003-103677A